Why is the 8086 not equivalent to x86? PCLMULHQHQDQ is from the CLMUL extension, which only began appearing in CPUs in the early 2010s - are CPUs from before then not x86?
x86 is an overarching group. Each processor is backwards compatible, I believe, so a 486 can run 8086 code, but they are not equivalent. If I download an x86 version of a program, I don't expect it to be written only in 8086 instructions
When you download an x86 program you're making a lot of other assumptions too, such as what the target operating system and hardware are. Even 8086 MSDOS software won't directly work in this emulator because it's not emulating DOS nor an IBM compatible, it has it's own addresses for the I/O. It's still x86 though.
I wasn't sure whether to address the disconnect in the FAQ - I wanted it to be short and readable.
The idea is that, since a long time ago, there has always been demos that prove turing completeness and other programmy qualities in CSS, but that which people dismiss as requiring user inputs. The ones around by the time the comment got made were definitely at the "keep on clicking on the same spot on the screen" level - essentially just providing a clock.
And seeing discussion from after Jane Ori's hack, many still claim that even as much as hovering your mouse on a specific part of the screen makes css not a programming language.
"providing a clock" is not something to dismiss though. Arithmetic plus looping will give you a Turing machine, so you do need both or you're just showing the ability to do arithmetic.
And a proper Turing machine doesn't need an extra line of template html for each iteration. It's much easier to forgive finite memory, since a small amount of memory can go for billions of years while an iteration limit runs out fast.
This one passes all the bars, but I do think the bars were overall legitimate.
> many still claim that even as much as hovering your mouse on a specific part of the screen makes css not a programming language.
clock != looping, those examples already loop (dont need a line per iteration), but just dont have a built-in clock
and requiring a clock is imo dismissable, because pretty much all modern technology needs a clock too (either from the power grid, or from a hardware component designed for it)
Sure, we can separate loops from clocking for the most part. But it doesn't really change the analysis. These loop. The stuff from several years ago didn't loop properly.
As a tangent though, the system is already powered, you shouldn't need a secondary power source to make your Turing machine go. Something there still feels incomplete, like it probably passes but with an asterisk. But that distinction doesn't matter for CSS since it can self-clock.
The instruction matrix they provide only includes 8086 instructions, not 186, 286 etc, which are all x86, hence the x at the start. From that wikipedia article, "The term "x86" came into being because the names of several successors to Intel's 8086 processor end in "86", including the 80186, 80286, 80386 and 80486. Colloquially, their names were "186", "286", "386" and "486"."
The point is that the 8086 doesn't have anything close to the instruction set now referred to as x86_64 or even x86_32. Asking which it is is asking which instruction set it implements. The answer is that it implements the 8086 instruction set.
Saying this is an "x86 CPU emulator" is misleading, even if technically an 8086 is an example of the x86 family. To avoid the misleading ambiguity you'd have to say something like "emulates a member of the x86 family", at which point you may as well just say "8086 emulator".
I think x86 is still good because it's easily understandable. If I say it's an 8086 emulator, people who aren't familiar with the 8086 aren't gonna go "oh so like an older version of the same x86 on my computer". And "Show HN: CSS program that emulates a CPU that's a member of the x86 family" doesn't roll off the tongue.
I don't think calling it x86 is misleading, and this is coming from the perspective of someone who dabbles in rev and pwn of x86.
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